This paper proposes a design of energy balance circuit for two adjacent Lithium-ion battery cells in the cell string based on the modifying of the bidirectional CuK converter principle. This design only uses one MOSFET to transfer energy between two cells in a direction controlled by the first relay, second relay controls the cutting energy balance circuit off the cells when they have the same energy level. The control command sent by the management battery system (BMS) to the energy balance circuit via an RS485 communication protocol controls the direction of transferring energy, the amplitude of the balance current, the frequency and duty of PWM, the PWM signal applied to MOSFET is programmed by a microprocessor PIC18F2685. This design overcomes some disadvantages caused by applying the principle of bidirectional CuK converter to design the energy balancing circuit, these are the need for a multiple level DC source to open MOSFETs and issue of the energy loss on the elements of energy balance circuit. This design is also easy to expand for the battery string with a large number of cells. The energy balance control strategy can be implemented directly by each the energy balance circuit or remotely by BMS using RS485 communication. The experimental results of online optimal energy balance control based on state of charge (SoC) feedback for 07 SAMSUNG 22P battery cells connected in series are presented to prove the efficiency of the energy balance circuit design for two adjacent cells proposed in this paper.
Citation: Chi Van Nguyen, Thuy Nguyen Vinh. Design of energy balancing circuit for battery cells connected in series based on modifying the bidirectional CuK converter[J]. AIMS Energy, 2022, 10(2): 219-235. doi: 10.3934/energy.2022012
This paper proposes a design of energy balance circuit for two adjacent Lithium-ion battery cells in the cell string based on the modifying of the bidirectional CuK converter principle. This design only uses one MOSFET to transfer energy between two cells in a direction controlled by the first relay, second relay controls the cutting energy balance circuit off the cells when they have the same energy level. The control command sent by the management battery system (BMS) to the energy balance circuit via an RS485 communication protocol controls the direction of transferring energy, the amplitude of the balance current, the frequency and duty of PWM, the PWM signal applied to MOSFET is programmed by a microprocessor PIC18F2685. This design overcomes some disadvantages caused by applying the principle of bidirectional CuK converter to design the energy balancing circuit, these are the need for a multiple level DC source to open MOSFETs and issue of the energy loss on the elements of energy balance circuit. This design is also easy to expand for the battery string with a large number of cells. The energy balance control strategy can be implemented directly by each the energy balance circuit or remotely by BMS using RS485 communication. The experimental results of online optimal energy balance control based on state of charge (SoC) feedback for 07 SAMSUNG 22P battery cells connected in series are presented to prove the efficiency of the energy balance circuit design for two adjacent cells proposed in this paper.
[1] | Rahimi EH, Ojha U, Baronti F, et al. (2013) Battery management system: An overview of its application in the smart grid and electric vehicles. IEEE Ind Electron Mag 7: 4–16. https://doi.org/10.1109/MIE.2013.2250351 doi: 10.1109/MIE.2013.2250351 |
[2] | Rivera Barrera JP, Muñoz Galeano N, Sarmiento-Maldonado HO (2017) SoC estimation for lithium-ion batteries: Review and future challenges. Electron 6: 102–120. https://doi.org/10.3390/electronics6040102 doi: 10.3390/electronics6040102 |
[3] | Alvarez DA, Estévez B, Adyr A, et al. (2020) A review of battery equalizer circuits for electric vehicle applications. Energ 13: 5688–5705. https://doi.org/10.3390/en13215688 doi: 10.3390/en13215688 |
[4] | How Lithium-Ion batteries in EVs catch fire. Available from: https://adreesh-ghoshal.medium.com/how-lithium-ion-batteries-in-evs-catch-fire-9d166c5b3af1. |
[5] | Wu TZ, Ji F, Liao L, et al. (2019) Voltage-SOC balancing control scheme for series-connected lithium-ion battery packs. J Energy Storage 25: 100895. https://doi.org/10.1016/j.est.2019.100895 doi: 10.1016/j.est.2019.100895 |
[6] | Hauser A, Kuhn R (2015) Cell balancing, battery state estimation, and safety aspects of battery management systems for electric vehicles. Adv Battery Technol Electr Veh 2015: 283–326. https://doi.org/10.1016/B978-1-78242-377-5.00012-1 doi: 10.1016/B978-1-78242-377-5.00012-1 |
[7] | Shang Y, Zhang C, Cui N, et al. (2015) A cell-to-Cell battery equalizer with zerocurrent switching and zero-voltage gap based on quasi-resonant LC converter and boost converter. IEEE Trans Power Electron 30: 3731–3747. https://doi.org/10.1109/TPEL.2014.2345672 doi: 10.1109/TPEL.2014.2345672 |
[8] | Cao J, Schofield N, Emadi A (2008) Battery balancing methods: A comprehensive review. IEEE Vehicle Power and Propulsion Conference 2008: 1–6. http://doi:10.1109/VPPC.2008.4677669 doi: 10.1109/VPPC.2008.4677669 |
[9] | Ouyang Q, Chen J, Xu C, et al. (2016) Cell balancing control for serially connected lithium-ion batteries. American Control Conference (ACC), 3095–3100. https://doi:10.1109/ACC.2016.7525393 doi: 10.1109/ACC.2016.7525393 |
[10] | Gallardo-Lozano J, Romero-Cadaval E, Milanes-Montero MI, et al. (2014) Battery equalization active methods. J Power Sources 246: 934–949. https://doi.org/10.1016/j.jpowsour.2013.08.026 doi: 10.1016/j.jpowsour.2013.08.026 |
[11] | Moore S, Schneider P (2001) A review of cell equalization methods for lithium ion and lithium polymer battery systems. SAE 2001 World Congress 0959: 1–7. https://doi.org/10.4271/2001-01-0959 doi: 10.4271/2001-01-0959 |
[12] | Sanjaya M (2006) Switching power supplies A to Z, 1st edition, eBook, ISBN-9780080461557. Available from: https://www.elsevier.com/books/switching-power-supplies-a-z/maniktala/978-0-7506-7970-1. |
[13] | Maksimovic D, Cuk S (1991) A unified analysis of PWM converters in discontinuous modes. IEEE Trans Power Electron 6: 476–490. https://doi.org/10.1109/63.85890[A1] doi: 10.1109/63.85890 |
[14] | Wu ST, Chang YN, Chang CY, et al. (2019) A fast charging balancing circuit for LiFePO4 battery. Electron 8: 1144. https://doi.org/10.3390/electronics8101144 doi: 10.3390/electronics8101144 |
[15] | Guo Z, Zhu H (2012) An application of communication system on the navigation light's filament status based on RS-485. 2nd International Conference on Remote Sensing, Environment and Transportation Engineering, 1–3. https://doi.org/10.1109/RSETE.2012.6260381 doi: 10.1109/RSETE.2012.6260381 |
[16] | Chi NV, Thuy NV (2020) Soc estimation of the Lithium-Ion battery pack using a Sigma point Kalman filter based on a cell's second order dynamic model. Appl Sci 10: 1896. https://doi.org/10.3390/app10051896 doi: 10.3390/app10051896 |
[17] | Christof B, Helmut M (2000) SQP-methods for solving optimal control problems with control and state constraints: adjoint variables, sensitivity analysis and real-time control. J Comput Appl Math 120: 85–108. https://doi.org/10.1016/S0377-0427(00)00305-8 doi: 10.1016/S0377-0427(00)00305-8 |
[18] | Constrained nonlinear optimization algorithm, 2022. Available from: https://www.mathworks.com/help/optim/ug/constrained-nonlinear-optimizationalgorithms.html. |
[19] | Rahman I, Riawan DC, Ashari M (2019) Design and implementation of DC-DC bidirectional Cuk converter with average current mode control for lead acid battery testing. International Seminar on Intelligent Technology and Its Applications (ISITIA) 2019: 183–188. https://doi.org/10.1109/ISITIA.2019.8937200 doi: 10.1109/ISITIA.2019.8937200 |